Figure 5.

Single and multinucleotide substitutions at CC photodimers. (A) A schematic of proposed mutational processes at CC dimers. hPol η inserts two dAMPs at the template dimer regardless the deamination status. After the photoreversion, yPol δ can insert dAMP opposite U, which was created only at 3′ side of the CC dimer. (B) Frequencies of multinucleotide deletions (Del) and multinucleotide substitutions (Sub) that were produced at indicated dipyrimidine template sites on the ‘1st hit only’ template in the reaction containing yPol δ, hPol η, and yPol ζ (shown in Figure 4B). Mean +SD are shown (n of each dipyrimidine sites are indicated under the graph). (C) Frequencies of dinucleotide substitutions at individual CpC template sites produced in the same reaction as (B). Yellow bars are CC>TT substitutions, and blue bars (although barely recognizable) are all other multinucleotide substitutions. (D) Frequencies of the CC>TT substitutions in the same reactions as in Figure 4B-M (mean + SD, n = 17, ****P < 0.0001; One-way ANOVA with Dunett's multiple comparison test to the left-most column in each section). Experimental conditions are indicated under the graph, in which the 2nd hit was made by either UVB (‘B’) or UVC (‘C’). (E) Frequencies of the C>T transition at 3′C or 5′C of CpC sites in the corresponding reactions in (D). Only CpC sites that had no adjacent pyrimidine (RpCpCpR context where R = purine, underlined in (C)) were analysed (mean +SD (n = 7), *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001; two-way ANOVA with Dunett's multiple comparison test). (F) Illustration of CT dimer to produce C>T transition by either TLS or deamination. (G) The ratio of C>T transition frequencies in the absence/presence of premixed hPol η + yPol ζ (TLS Pols) was calculated in two sequence contexts (TpCpR and RpCpT, where R = purine) from data in Figure 4K and J (mean +SD (n is indicated under the graph), ****P < 0.0001; two-tailed unpaired t-test).